disposal concepts and options

IAEA International Atomic Energy Agency

LILW DISPOSAL CONCEPTS AND

OPTIONS

EXAMPLES AND KEY SAFETY ARGUMENTS

P. ORMAI IAEA, Waste Technology Section

IAEA

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Presentation aims

• To provide examples of different types of LILW disposal concepts and facilities in all over the world

• To consider the reasons and safety arguments for the different facility types

IAEA

Disposal

Disposal options are designed to contain the waste by

means of passive engineered and natural features and

isolate it from the accessible biosphere to the extent

necessitated by the associated hazard.

3

The term ‘disposal’ refers to the emplacement of radioactive

waste into a facility or a location with no intention of

retrieving the waste.

(The term disposal implies that retrieval is not intended; it does not mean

that retrieval is not possible.)

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Disposal system: site, engineering, control

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ISOLATION

RETARDATION

containment

Radioactive

waste

receptor

Isolation: • means design to keep the waste and its

associated hazard apart from the

accessible biosphere.

• It also means design to minimize the

influence of factors that could reduce

the integrity of the disposal facility.

Containment : • implies designing the disposal facility to

avoid or minimize the release of

radionuclides.

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Why disposal?

6

• Long time scales for decay

• Ethics / sustainability / security

• polluter pays (this generation pays)

• future generations may lack resources

• societal breakdown

• put beyond use

Common drivers:

• offer final solution (provide disposal capacity)

• increase safety / security

• save money

IAEA 7

Quantitative guidance

• Exempt waste: Criteria from BSS – quantities in RS-G-1.7

• Very short lived waste:: Less than 100 days half life

• Very low level waste: Up to 100x clearance levels (radioactivity level

close to that of naturally occurring radioactivity: between 1 and 100 Bq/g).

• Low level waste: • Near-surface disposal (less than 30 m depth)

• Institutional control for 100 – 300 years

• Less than 400 Bq/g long lived nuclides

• Intermediated level waste:

• need a greater degree of containment and isolation from the biosphere than

provided by near surface disposal

• disposal between deeper than 30 – 50 m (typically a few hundred meters)

• High level waste:

• Heat generation significant

• Activities around 5x104 to 5x105 TBq/m3

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Selection of a disposal option

The selection of a disposal option depends on many factors,

both technical and administrative, such as:

• waste characteristics and inventory

• radioactive waste management policy

• overall disposal strategy in the country (how many facilities)

• national legislative and regulatory requirements

• political decisions

• social acceptance

• the conditions of the country such as climatic conditions

and site characteristics, availability of suitable host media.

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Disposal design aim

• All disposal designs aim to prevent or reduce interaction

between water and waste.

• There are many ways of doing this:

• choice of site (arid region, unsaturated, mountainous site, etc.),

• choice of depth (near surface above/ below grade, intermediate

depth, deep geological),

• water resistant cap (runoff drainage layer, clay barrier)

• long-lived containment (BOSS concept).

• A primary issue also is protection of inadvertent human

intruder and the degree to which a combination of depth of

disposal, institutional controls, and engineered barriers can

be relied upon to prevent or minimize this exposure

scenario.

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Graded approach

• Decisions on disposal technology selection should follow a graded

approach. The following principles are suggested to implement such

an approach:

• Wastes are disposed using the simplest disposal concept available,

consistent with the hazards present and for which safety and environmental

protection can be demonstrated.

•

• The most hazardous wastes are disposed using greater levels of

engineering to provide for increased containment and/or are disposed at

greater depth to increase isolation from the surface environment;

• Where existing disposal facilities are available, consideration is given to

using them before developing new disposal facilities. This may require

additional analyses and regulatory authorizations not addressed by existing

waste acceptance criteria and operating procedures;

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IAEA Waste classification scheme (1)

• The first reference, in my view, should be the IAEA Waste

classification scheme which provides a general system of

classification accommodating various waste types and

disposal solutions.

• This scheme offers a useful initial consideration despite it

identifies only boundaries & provides quantitative guidance

and does not prescribe specific disposal solution for certain

waste types (as specific safety assessment for each

disposal facility is required).

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IAEA Waste classification scheme (2)

General system of classification accommodating various waste types and disposal

solutions

Identify boundaries & provide quantitative guidance

Does not prescribe specific disposal solution for certain waste types –

specific safety assessment for each disposal facility required

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Stepwise approach (1)

• Logically the next step is to explain that selection of a

disposal option may start with a quick screening by using a

simple matrix.

• The task is to adapt the possible disposal solutions to the

particular waste streams.

• Based on the IAEA Waste classification scheme VSLW,

VLLW, LLW, ILW, HLW can be differentiated (special

consideration should be given to DSSR, NORM/TENORM

waste)

• When assessing the disposal options, consideration should

also be given to the volume of waste to be disposed of

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• Commensurate with the diverse range of wastes, a diverse range of

disposal solutions have been implemented and proposed for the broad

range of LILW, examples of such being:

• landfill

• unlined or engineered trenches

• engineered surface or subsurface facilities relatively shallow cavities,

former mines, disposal in geological formations and

• borehole disposal.

• geological disposal

• In all cases it is important to recognize the unique hazards of the

specific sub-categories of LILW, for example ILW containing

predominantly short lived radionuclides may not require the same

disposal methods as ILW containing predominantly long-lived

radionuclides. In case of DSRS the half-life (short or long lived) and

the activity (SHARS) plays a key role.

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• The next step is to match the possible disposal

solutions to the particular waste streams.

• Safety is the fundamental objective of radioactive waste

disposal. Several options can be ab ovo excluded from

safety consideration point of view.

• Other options can be ruled out on the grounds of technical

reasons (not feasible, difficult to implement, etc.).

• Based on the generic safety considerations, the

characteristics and volume of waste potentially

acceptable or preferable options can then be identified.

• There might be options which need to be more closely

assessed from technical and economic aspects.

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Best option

• One should be, however, aware that the notion of an “optimal”

disposal solution is elusive.

• Deciding what would be an optimal solution is complicated by many

factors that cloud the decision process (e.g., specific waste streams,

policy constraints, and public acceptance, siting constraints, the,

resources available).

• The legal framework can often prescribe the range of disposal solutions

that can be examined. In the end, the disposal system is either safe or

not safe, as determined by regulatory review.

• Therefore this approach is only indicative, and decisions on waste

disposal will need to be made on a case-by-case basis taking into

account actual conditions, waste characteristics, applicable regulatory

requirements the results of a preliminary safety assessment.

•

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Radioactive waste

stream

END POINT

Long-

term

storage

Decay

storage

Surface

trench

Engineered

surface

facility

Intermediate

depth facility

Geologic

repository BOSS Others

2. VSLW Low volume

Large volume

3.VLLW Low volume

Large volume

4. LLW Low volume

Large volume

5. ILW

Low volume

Large volume

6. HLW

DSRS

Short-lived

Long-lived

SHARS

NORM Low volume

Large volume

Uranium

M&M

Low volume

Large volume

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Radioactive waste

stream

END POINT

Long-

term

storage

Decay

storage

Surface

trench

Engineered

surface

facility

Intermediate

depth facility

Geologic

repository BOSS Other

VSLW Low volume

Large volume

VLLW Low volume

Large volume

LLW Low volume

Large volume

ILW

Low volume

Large volume

SNF/HLW

DSRS

Short-lived

Long-lived

SHARS

NORM Low volume

Large volume

Uranium

M&M

Low volume

Large volume

preferable acceptable Possible but needs to be assessed

from technical or economic aspects Not possible for technical reason Not possible for safety reason

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Exempt waste

• If radioactive materials (waste) meet certain criteria, they

can be exempted.

• If a radioactive material is exempted, it can be disposed of

as if it was not a radioactive material—e.g., if the material

would be municipal solid waste if it were not radioactive,

then it can be disposed of in an authorized municipal solid

waste disposal facility when it receives an exemption.

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Radioactive waste

stream

END POINT

Long-

term

storage

Decay

storage

Surface

trench

Tailing

dam

Enginered

surface

facility

Intermediate

depth facility

Geologic

repository BOSS

VSLW Low volume NR ++ + + + NR NR NR

Large volume NR ++ + + NR NR NR NT

VLLW Low volume NR N ++ ++ + NR NT NR

Large volume NR N ++ ++ + NR NT NT

LLW Low volume + N + + ++ ++ + +

Large volume + N NR NR ++ ++ + NT

ILW

Low volume + N N N N ++ ++ +

Large volume + N N N N ++ ++ N

SNF/HLW + N N N N N ++

DSRS

Short-lived + + + NR ++ + NR +

Long-lived + N N N + ++ ++ ++

SHARS + N N N N ++ ++ ++

NORM Low volume NR N ++ ++ + + NR NR

Large volume NR N ++ ++ NR NR NR NT

Uranium

M&M

Low volume NR N + ++ + + + NR

Large volume NR N + ++ NR NR NR NT

preferable acceptable Not possible for safety reason Possible but needs to be assessed

from technical or economic aspects Not possible for technical reason

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Radioactive waste

stream

END POINT

Decay

storage

Surface

trench

Tailing

dam

Engineered

surface

facility

Intermediate

depth facility

Geologic

repository BOSS

VSLW

Low volume

Large volume

VLLW

Low volume

Large volume

Disposal of VSLW and VLLW

In some countries, VLLW is disposed of in purpose-built disposal facilities,

in the form of earthen trenches with engineered covers.

In other MS, it is disposed of with other waste types, e.g. LLW.

The decision on disposal method is usually made on economic and/or

regulatory grounds.

preferable acceptable Not possible for safety reason Not possible for technical reason Possible but needs to be assessed

from technical or economic aspects

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Managing decommissioning waste

• Decommissioning and dismantling a 1000 MWe power

station: 5000 – 10 000 m3

• Amount and activity of waste depend upon the selected decom.

strategy: immediate or deferred

• The longer one waits before dismantling and disposal, the

higher is the fraction of waste that can go to conventional

disposal sites, or VLLW site, rather than to LLW

repository (more expensive).

VLLW disposal facilities designed to accept voluminous

rubble from decommissioning activities.

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Oskarshamn, Forsmark, Ringhals and Studsvik (Sweden)

• Above ground facility, non-permeable

engineered bottom plate, leachate directed

to external infiltration bed

• Cover is a mixed layer of bentonite with a

plastic liner, covered with a drainage layer

and a protective layer of moraine and soil

• External infiltration bed with a mixture

Drainage material

Protective layer

Drainage material

Drainage layer

Bentonite & plastic liner

bentonite liner

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Morvilliers (France)

• From the operation and decommissioning of

nuclear facilities

• NORM waste

• Very low specific-activity levels - below a few

hundreds of Bq/g

• Disposal requires no special processing or

conditioning

• Some of the wastes are compacted into bales

and wrapped in polyethylene

1). geomembrane, 2) Clay-based materials 3) 2.5 m-thick clay backfill, 4) 30-cm-thick layer of soil and grass

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VLLW arising by decommissioning of Japan

Power Demonstration Reactor (JPDR)

Japan trench-type VLLW repository

EL- CABRIL – Spain

171,500 m3 - 52 % (90,000 m3) can be treated as VLLW

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Radioactive waste

stream

END POINT

Decay

storage

Surface

trench

Tailing

dam

Engineered

surface

facility

Intermediate

depth facility

Geologic

repository BOSS

LLW

Low volume

Large volume

A very wide range of specific activities (~7 orders)

Low amounts of long-lived radionuclides

The boundary between LLW and ILW is not precise

Limits on acceptable levels of long-lived (and other) nuclides will be depend on

the design and location of the particular facility

Options for the disposal of LLW

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Near-surface disposal: facility types

Near-surface disposal facility types: trenches,

engineered vaults, mounds, silos

An engineered or earthen cap is placed over

the waste containers to minimize water

infiltration.

Subsurface disposal facilities: Some

countries prefer disposing of LLW in

subsurface facilities or co-locating LLW with

ILW in deeper facilities.

Permissible activity limits (WAC) generally determined by

post-closure safety assessment:

• total site activity – natural discharges

• specific activity – inadvertent human intrusion

• may be some operational limitations but usually these can

be overcome by remote working

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earthen trenches

(with or without engineering)

30

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Trench type disposal concepts

NTS - Area 5 (USA)

Peña Blanca (USA)

Richland (USA)

Ezeiza (Argentina)

Vaalputs (South Africa)

L’Aube (France)

El Cabril (Spain)

31

Australia

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US Ecology Richland, Hanford - USA

• Arid desert environment

• Large trenches

• Waste containers are placed up

to 13.7 m deep in trenches, and

the waste layer stops 2.4 m

below the land surface.

• LLW, NORM and accelerator

wastes

• Additional concrete engineered

barriers for Ra bearing wastes

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VAALPUTS – South Africa

• Arid environment

• Reliance on geological features

• Much less engineering

• Typically lower cost

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Australia

• Dry environment

• Remote areas

• Little possibility of leaching or exposure

• Small to large trenches

• Low volumes of drummed wastes from

mining and uranium ore processing

• Occasional disposals as and when

wastes arise

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ABOVE OR BELOW GRADE

TEMPERATE SITES

35

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Centre de la Manche (France)

• Wet environment

• Early units: trenches

• Waste drums stacked in a tumulus

(mound) formation

• Greater reliance on engineered features

• Disposal began before modern

concepts of safety assessment or safety

cases

• On-going monitoring and surveillance

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Below Grade Vault

• Similar engineering functions to Above Grade Vault

• Waste emplaced below ground, as in trench disposal

• Limited application if shallow water table

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Drigg – UK Centre de l’Aube – France El Cabril – Spain

Rokkasho – Japan Vector – Ukraine Hanford – USA

Mohovce – Slovakia Dukovany – Czech Republic

Püspökszilágy – Hungary

All follow essentially the same design:

• above or just below grade concrete-lined vaults

• split into separate compartments

• mobile weatherproof roof during operation

• multilayer cap

• drainage systems (above and below waste)

• cement encapsulation and backfill

Typical examples: engineered vaults

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Centre de l’Aube (France) 1.

• Disposal facility design • On surface disposal facility (1 000 000 m3)

• Single layer of engineered concrete vaults

• Single foundation raft located >30 cm above

the water table

• Vault walls made of reinforced concrete

• Concrete cover placed over the wastes once

the vault is filled

• Waste emplacement

• Automated emplacement of wastes in drums

• Mobile weather protection structure (mobile roof)

• Backfilled with gravel or injected with concrete

grout

Separate drainage networks for rain waters

and waters at risk of radionuclide

contamination

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Centre de l’Aube (France) 2.

Hydrogeological context:

• Disposal facility located above the highest levels of groundwater table

• Draining layer (clayey sand) lying on an impermeable substratum (clay)

• Argillaceous sand offers a good compromise between permeability (10-6

m/s) and radionuclide retention

• Groundwater flow is well constrained and drains to a single receptor (the

Noues d’Amance river)

• Lower (regional) aquifers isolated thanks to impermeable argillaceous layers

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DRIGG - UK

This is a typical below grade vault

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ROKKASHO – Japan

Shallow ground vault-type, below groundwater table

The spaces between the drums are sealed by a

cement based mortar grout.

Once the reinforced concrete lid is formed, these

modules are backfilled by bentonite-soil mixture.

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EL-CABRIL – Spain

Drainage networks for rain waters

and potentially contaminated water

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MOCHOVCE - Slovakia

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DUKOVANY - Czech Republic

Close vicinity of the NPP

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Dessel (Belgium)

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CAVERNS

Abandoned underground mines or quarries

Purpose-built rock caverns

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RICHARD - Czech Republic

Former limestone mine subsequently

enlarged to act as a munitions factory

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Silos

• Examples:

• L/ILW disposal at Olkiluoto (Finland)

• L/ILW disposal at SFR Forsmark (Sweden)

• L/ILW disposal at Wolsong (Korea)

• L/ILW disposal at Vrbina-Krško (Slovenia)

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FORSMARK – Sweden

One cavern contains LLW enclosed in

standard ISO containers.

3 of the caverns receive ILW waste.

The concrete silo is also intended for ILW.

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,

The repository is located at the depth of appr.

110 m in granite bedrock.

Entrance from the NNP site

The repository consists of two tunnels for solid

LLW and a cavern for immobilised ILW.

LOVIISA - Finland

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Olkiloutu - Finland

• L/ILW disposal at 60 to 100

meters depth

• Waste generated during the

operation and maintenance of

nuclear power plants

• LLW is compressed into 200-litre

drums

• Non-compressible waste is

packed into steel or concrete

boxes

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WOLSONG - Korea

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Vrbina-Krško – Slovenia

• Site on a river plain from a community

volunteering process

• Silo concept assessed as both feasible and

safe for the inventory of L/ILW to be disposed

• A surface disposal concept was rejected as

being too vulnerable to flooding and erosion

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HIMDALEN - Norway

• Not nuclear country

• Disposal facility for institutional waste

• Storage for Pu-bearing waste

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Bátaapáti - Hungary

Host rock: granite,

Disposal depth: ~200-250 m

Access: with two inclined tunnels

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Deep geologic

facilities

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KONRAD - Germany

58

Abandoned iron ore mine

Emplacement dept: 800-1300 m

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Kincardine - Canada

Capacity: 200 000 m3

LLW and ILW

200 m low permeability

shale

680 m depth in limestone

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Disposal at depths of greater than several tens of metres is generally

considered to be the most appropriate option for ILW.

While repositories specifically for ILW exist in some countries, in others, co-

disposal with spent fuel and high level waste is being considered.

Options for the disposal of ILW

Radioactive waste

stream

END POINT

Decay

storage

Surface

trench

Tailing

dam

Engineered

surface

facility

Intermediate

depth facility

Geologic

repository BOSS

ILW

Low volume

Large volume

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DOE Defense Transuranic Waste Disposal Facility

665 m underground in salt formation

Waste Isolation Pilot Plant (WIPP) - Carlsbad, NM USA

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Radioactive waste

stream

END POINT

Decay

storage

Surface

trench

Tailing

dam

Engineered

surface

facility

Intermediate

depth facility

Geologic

repository BOSS

NORM

Low volume

Large volume

Disposal of NORM waste (1)

Where is the NORM from: • Uranium mining and milling

• Uranium overburden and mine spoils

• Phosphate industry wastes (phosphate fertilizers and potash)

• Coal mines (coal ash)

• Oil and gas production scale and sludge

• Waste water treatment sludge

• Metal mining and processing waste (Zinc & lead mining, Al mines)

• Geothermal energy production waste.

• Scrap metal release and recycling

• Rare earth element mining (rarer earth element metallurgy)

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• The mining and processing of minerals give rise to large amounts of waste

containing elevated concentrations of naturally occurring radionuclides (NORM,

TENORM).

• This includes waste from U and Th mining and milling, residues from other mining

activities, from the burning of coal and the extraction of metals from raw materials.

• The characteristics of NORM waste differ from those arising from nuclear power

station operations and from the institutional use of radionuclides in several

important respects:

• the volumes are usually much larger, restricting management options both

technologically and economically;

• the half-lives of naturally occurring radionuclides in NORM waste are much longer than

the mainly fission product radionuclides — such that radioactive decay does not result in

a reduction of the associated radiological risks within foreseeable periods of time.

• This means that NORM waste is not suitable for disposal in the ‘classic’ type of

near surface repository. In many cases, the health risks to be addressed in the

management of this waste also come from the chemically toxic or carcinogenic

substances present.

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• The principle management options for NORM waste are recycling and

disposal.

• Recycling is only possible for waste with a low radioactivity content and suitable

physical or chemical properties, which limits this option.

• For economical and technical reasons, near or above surface facilities have to be used

in most cases.

• Only for the special cases of waste with high radioactivity levels and comparatively low

volumes is underground disposal a relevant management option.

• The spectrum of options for the disposal of large amounts of NORM

waste ranges from doing almost nothing, if this is acceptable from a

radiological standpoint, to very expensive solutions.

• However, the low cost options are often associated with a significant

environmental impact and the increased costs of the other solutions may

have to be accepted as a way of reducing these impacts. • Consequently, the choice of a suitable disposal option requires that a balance is struck

between long term risk from the waste and the financial costs of implementing a

disposal solution.

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NORM waste is generally deposited in consolidated and over-covered piles or sludge beds, or

purpose designed repositories with lined cells and protective capping.

In some cases, the waste has been disposed of by using it to backfill disused underground

mines.


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As it is not feasible to move such large amounts of material, the waste tends to be

disposed of on the site of its generation.

No international consensus on applicable doses.

Stewardship is needed perpetually (as opposed to other near-surface disposal) due to

LL nuclides on surface.

Mukim Belanga, Malaysia NORM Disposal at Sewaqa

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Radioactive waste

stream

END POINT

Decay

storage

Surface

trench

Tailing

dam

Engineered

surface

facility

Intermediate

depth facility

Geologic

repository BOSS

DSRS

Short-lived

Long-lived

SHARS

Disposal of DSRS

Disposal options for DSRS vary depending on the activity levels and types of

radionuclides in the sources.

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Problem Sources

Causingmost

problems

Causingproblems

Normallyno

problem

Littleconcern

Noconcern

1kBq 1Mbq 1Gbq 1Tbq 1Pbq

Very weak Weak Medium Strong Very strong

Brachytherapy

Industrialradiography

Tele-therapy

Moisturedetectors

Well logging

Industrial guages

Irradiators forResearch Industry

Calibration sources

Consumerproducts

Source

strength

Scale of

problem

1 Ci 1000 Ci

IAEA

I Surface

II Deep

III Borehole

Intermediate

depth disposal?

Disposal options

Near surface repositories may be

suitable for low activity, short-lived

sources.

Concentration limits

β/γ - typically 10 MBq kg-1

α – up to 50 times less than this

Total activity limits

β/γ - typically 100’s PBq

α - could be 1000 times less than this

For long-lived DSRS with activity levels

exceeding the criteria for disposal in a near

surface repository, GD is the preferred

option.

Acceptable DSRS for deep disposal

No limit in principle BUT

Purpose built deep repository for DSRS: out of the question

Use of existing facilities. where they exist!

Regional or international repositories. will they happen ?

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Existing BOREHOLE facilities

• In the former USSR: „RADON” facilities

• USA: Greater confinement boreholes

– The Nevada test site and WIPP

• South Africa – Pelindaba

• Western Australia – Mt Walton “Intractable Waste

Facility”

• Russian Federation: large diameter borehole (LDB)

IAEA

„RADON” facilities

4.6 m

3.6 m 8 4 array

16 pcs wells Depth = 6 m Internal diameter = 38 mm

16 pcs wells Depth = 6 m Internal diameter = 100 mm

North

Typical arrangement in the FSU

Long-lived sources short-lived sources

Co-disposal in Hungary

IAEA Mt Walton East, Australia

Greater Confinement Savannah River

2 m diameter

6 m deep

Nevada Test Site

3 m diameter

37 m deep

21 m closure

IAEA

DOE TRU Waste Disposal Facilities – Greater

Confinement Boreholes

• Constructed at Nevada Test Site and received

TRU waste (239Pu) and high-activity low-level

radioactive waste (200 m3)

• 13 boreholes constructed, 9 of which received

waste

• Range from 3 to 3.6 m in diameter, and extend to

a depth of 36 m

• Waste packages were placed in the boreholes

from the bottom to appr. 21 m from the surface

• Used from 1984 to 1989

IAEA

Borehole capabilities

RADON small 4-6 m PBq Cs-137

source Co-60

W Australia 8 m GBq Cs-137

GBq Am-241

Greater 21 m PBq TRU

confinement

(Nevada Test Site)

disposal

intermediate depth

disposal

storage

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BOSS CONCEPT: Safety Philosophy

‘Borehole facilities offer safe, simple,

economic alternative for all DSRS

Easier’ disposal derives from the small volume

and nature of the waste

No decrease in safety standards, these to be

set by national authorities, backed up by

international guidance, as usual

Existing disposal solutions unsuitable or unacceptable for Cat

1&2 DSRS

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Concluding remarks

IAEA

Disposal Options

• Chosen disposal concept will depend on: • Nature of the waste

• Quantity of waste

• Site characteristics

• Other factors (e.g. socio-political)

Disposal is intended to be permanent, but a programme can be designed to

include retrievability (reversing the action of waste emplacement before or after

closure) and/or reversibility (reverse one or more steps in a repository

development at any stage).

Near-surface options should aim for passive safety through containment

and isolation but may include provision for an extended phase of monitoring

and control (lifetime generally 300 years, but depends !)

Underground options should be intrinsically and passively safe with

defence in depth (multiple barriers)

IAEA

All designs aim to prevent or reduce interaction between water and waste.

There are many ways of doing this:

• choice of site • arid region

• unsaturated, mountainous site (BUT saturated site can be OK)

• choice of depth • near surface above/ below grade

• intermediate or deep depth disposal

• water resistant cap • runoff

• drainage layer

• clay barrier

• long-lived containment (BOSS borehole)

IAEA

• Many ways to design repository: different geometries,

different configurations, different materials

• Different disposal systems have been developed, but no

unique design – several types exist suitable for different

conditions.

• Repository type/design depends on:

• Overall disposal strategy in the country (how many facilities?)

• Waste inventories

• The nature of the site (host media) and its surroundings

• Climate

• Legislative restrictions

• Political decisions

• Social acceptance

IAEA

• High reliance on ENGINEERED

BARRIERS, supported by natural

site characteristics

• Long term institutional control may

continue after repository closure to

ensure safety

• High reliance on NATURAL

BARRIERS, supported by

engineered and chemical barriers

• Possible post-closure monitoring,

but concept rely on passive safety

IAEA

Worth keeping in mind (1)

• There is a great deal of experience in near-surface

disposal

• There is no “best” design for a near-surface disposal

facility

• The design should reflect the circumstances and the level

of hazard or risk

• Available technologies must be assessed.

• Appropriate selection and optimization of technical options

is important in terms of safety, economics and efficiency.

• Technical options based on compliance with national

policies, available funding, human resources and

public sensitivities.

IAEA

Worth keeping in mind (2)

• Principal safety arguments include:

• Activity limitation and waste acceptance controls

• Isolation and containment of the wastes

• For at least a few hundred years

• Allows decay

• Limiting contact between the wastes and water

• For many facilities the final cap or cover is the key component

• Radionuclide retardation

• Appropriate management controls and regulatory processes

• The safety case should be developed and used to manage

facility operation and ensure safety requirements, limits,

criteria and conditions are met (Rob’s presentation)

IAEA

Thank you!

disposal concepts and options

Documents